1. Field of the Invention
The present invention relates to a device for the transvascular implantation and fixation of prosthetic heart valves having a self-expanding heart valve stent with a prosthetic heart valve at its proximal end.
2. Background Information
A device of this type is, in principle, known to medical technology. At present, biological or mechanical valve models are available to substitute for human heart valves which are usually fixedly sewn into the bed of the heart valve during a surgical procedure through an opening in the chest after removal of the diseased heart valve. In this surgical procedure, the patient's circulation must be maintained by a heart-lung machine, whereby cardiac arrest is induced during the implantation of the prosthetic heart valve. This consequently makes the surgical procedure a risky one coupled with the associated risks for the patients and a lengthy post-operative treatment phase. In particular, such a procedure cannot be performed on patients whose hearts are already too weak.
Minimally-invasive treatment procedures of recent development are characterized in particular by requiring a considerably shortened duration of anesthesia. One approach provides for implanting a self-expanding prosthetic heart valve with an artificial heart valve and a collapsible and expandable stent connected to the heart valve into the human body by means of an appropriate catheter system. The catheter system is used to guide such a self-expanding prosthetic heart valve through a femoral artery or vein to its site of implantation at the heart. After reaching the site of implantation, the stent, which consists for example of a plurality of self-expanding stent segments which can be bent relative one another in the longitudinal direction, can then be successively expanded. Following the expansion, anchoring hooks can for example support the anchoring of the prosthetic heart valve at least in the respective blood vessel close to the heart. The actual prosthetic heart valve itself is thereby in the direct proximal area of the stent.
Known for example from the DE 100 10 074 AI printed publication is a device for fastening and anchoring prosthetic heart valves, which is essentially formed from wire-shaped interconnected elements. The device provides for using various different arched elements in order to attain a secure retention and support for the prosthetic heart valve. To this end, the device described in this printed publication makes use of three identical pairs of arched elements, offset from one another by 120°. These arched elements are interconnected by means of solid articulations, whereby the solid articulations fulfill the function of pivot bearings. Additional arched elements bent opposite to each other are furthermore provided which form, rocker arms as equal in length as possible in order to achieve a secure anchoring of the arched elements even when subject to peristaltic actions on the heart and blood vessels and a solid sealing for an implanted and anchored prosthetic heart valve.
In the known solutions, however, there is a risk of heart valve implant malalignment. This essentially refers to the exact positioning and angular adjustment of the prosthetic heart valve to be implanted. In particular, it is only with immense skill on the part of the person performing the implantation—if at all—that a stent with the prosthetic heart valve at its proximal end winds up being positioned so precisely in the proximity of the patient's diseased heart valve that both sufficient lateral positioning accuracy as well as a suitable angular position to the prosthetic heart valve can be optimally ensured. The known solutions are also only conditionally suitable for explanting improperly or incorrectly positioned prosthetic heart valves. Such a process is usually only possible with great effort; in particular, a further surgical procedure is required.
Among other complications, an implantation malalignment of a less than optimally positioned prosthetic heart valve can lead to, for example, leakage or valvular regurgitation, which puts a substantial burden on the ventricle. Should, for example, a prosthetic heart valve be implanted too high above the actual heart valve plane, this can lead to occlusion of the coronary artery origination (coronaries) and thus to a fatal coronary ischemia with myocardiac infarction. It is therefore imperative for an implanted prosthetic heart valve to meet all the respective requirements for both the accuracy of the lateral positioning as well as the angular positioning.
In conventional implantation techniques in which self-expanding prosthetic heart valves are, for example, guided through a patient's femoral artery to the site of deployment at the heart in a minimally-invasive procedure, the prosthesis is usually introduced using a guide wire and catheters, whereby conventional balloon catheters can also be used. Although such a surgical introduction can be monitored and controlled, for example with fluoroscopy (Cardiac Catheterization Laboratory=CCL) or with ultrasound (Transesophageal Echocardiogram=TEE), oftentimes—due to the limited maneuverability of the prosthetic heart valve which is still in a collapsed state during the introduction procedure and despite being in the collapsed state is still of relatively large size—it is not possible to ensure the required positioning accuracy and especially the angular position to the prosthetic heart valve implant with the corresponding anchoring elements affixed thereto. In particular—as a result of a possible coronary artery occlusion—an angular misalignment to the implanted prosthetic heart valve from the optimum site of deployment can pose a threat to the respective patient.
In designing a prosthetic heart valve, special consideration must, in particular, be given to the substantial forces also acting on the prosthesis during the filling period of the cardiac cycle (diastole), necessitating a secure anchorage in order to prevent the implanted prosthetic heart valve from dislodging.
Hence on the one hand, the prosthetic heart valve must be able to be maneuvered as much as possible in the respective coronary artery during the implantation procedure so as to ensure optimum positioning accuracy and, on the other hand, the implanted prosthesis must be able to be firmly anchored at its site of implantation in order to effectively prevent subsequent prosthesis misalignment.
The present invention addresses the problem that the known devices for transvascular implantation and fixation of prosthetic heart valves are often not suitable for easily implanting a prosthetic heart valve in a patient's ventricle with the necessary positioning accuracy. In particular, the necessary lateral positioning accuracy and the angular position of the prosthetic heart valve can usually only be sufficiently guaranteed when the person performing the procedure has the corresponding experience. On the other hand, explanting a previously implanted prosthetic heart valve in a minimally-invasive procedure or accordingly correcting an incorrectly positioned prosthetic heart valve has to date only been possible with great effort, if at all.
On the basis of this problem as set forth, the present invention proposes a device which enables a prosthetic heart valve to be implanted into a patient in a minimally-invasive procedure in as simple a manner as possible, wherein an increased positioning accuracy to the prosthesis in the patient's ventricle can in particular be ensured. Such a device is to, in particular, reduce the risk of an incorrect deployment to the greatest extent possible.